Myocardial infarction results in irreversible loss of heart tissues or cardiomyocytes. Injured human hearts heal by scarring, which leads to remodeling and subsequently, heart failure. Heart failure remains the leading cause of morbidity and mortality in the US and developed world due to failure to adequately replace lost ventricular myocardium from ischemia-induced infarction. Unlike some fish and amphibians whose hearts can regenerate, adult mammalian cardiomyocytes have a limited capacity to regenerate from ventricular injury.
The progress in stem cell technology recently has enabled a solution by offering enormous availability of human cardiomyocytes derived from embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Advances in ESCs and iPSCs-derived cardiomyocytes (CMs) have rejuvenated the field of cardiac cell transplantation. However, before stem cell-based technology can be brought to clinical use, there is the challenge that the transplanted tissue consisting of derived cardiomyocytes fails to integrate and synchronize with the host. Studies and methods have been proposed to “train” cardiomyocytes towards maturation and integration, which raises a need to monitor the operation of entire hearts.
There are several methods to assess the myocardium, including imaging techniques (optical imaging, ultrasound, MRI, etc.), patch clamping and protein analysis. Although those above-mentioned approaches could deliver thorough information about the myocardium, they are more about the operation at the cell level and fail to give an overall operation of the heart. Accordingly, there is a need and desire for a quick and easy way to acquire information related to the operation of a subject's heart and to monitor the operation of the subject's heart.